Proteases: The mechanism of inhibition of bromelain by its specific protein inhibitor will be established. Two proteases from the venom of Crotalus adamanteus will be purified and characterized. Their role in the generation of the other venom enzymes will be determined. Lipolytic enzymes: the substrate specificity of pancreatic phospholipase A2 and snake venom phospholipase A2 of Crotalus adamanteus will be determined by using the changes in surface potential of monomolecular substrate layers for monitoring the reaction. The correlation between reactivity and phase changes of substrate monolayers will be used to determine the structure and orientation of phospholipid monolayers.